[import] support document.stylesheets in imported documents.

Source/core/html/LinkImport.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 114 matching lines @@
 bool LinkImport::isCreatedByParser() const
 {
     return m_owner && m_owner->isCreatedByParser();
 }
 
 bool LinkImport::hasLoaded() const
 {
     return m_child && m_child->isDone() && !m_child->loaderHasError();
 }
 
+bool LinkImport::ownsLoader() const
+{
+    return m_child && m_child->hasLoader() && m_child->ownsLoader();
+}
+
 } // namespace WebCore